Explorer holds that many, and it wasn't even an issue...however, with shark cages, the line will be a bit longer, so yeah I get where you're coming from. We'll see how it goes...I know people that were on Belle Amie a few months ago at Guadalupe and loved it. They travel more than anyone I know, and have pretty high standards...that helps.

I have the Nauticam NA-D810 and am very happy with it. All the controls are well placed, easy to use, smooth in operation, and have great feel. Right now I have the Sigma 15mm fisheye, Nikon 20mm 2.8 D, and 105VR as my underwater lenses. The sigma shoots great behind smaller domes, like my Zen 170mm, while the 20 (and the 16-35 I may get soon) need bigger domes so I picked up a Nauticam 8.5" (which may be a bit too small) recently to see how it goes. I don't really want a 230mm or bigger dome at this point.

I wouldn't use the Ikelite for my D810, as I don't like them, but many people do -- it's my preference.

I made my own from some 550 cord (aka parachute cord) and some XL bolt snaps that I had as spares for sidemount rigging. I followed a youtube video on how to make it, and it was actually pretty easy. I tested it by throwing it over a rafter and doing pullups with it. If it can hold me up, it'll hold my camera rig for sure!

I used my 20/2.8D in the Maldives a good bit, and am pretty happy with the results. I shot it behind a couple different Zen domes (170 and 200). I also shot the 16-35 (with the 200) and Sigma 15mm FE (behind the 170 and 200) -- a buddy of mine had his D810 rig and stuff so we traded lenses and ports over the northern atolls tour we were on.

These were both with my D810 and 20/2.8D - Nauticam Housing & two Z-240 strobes

I have a Thinktank Airport International 2.0, and while great it's a bit heavy. The Cinebag linked above is a good bag too, as it appears as a laptop bag and is generally not weighed as a carry on.

Carry on weight is becoming more and more important. Flying with Singapore Air I can carry on two pieces of 7kg each in business or one if flying economy, while Philippine air only allows one at 7kg and they're pretty strict about it, regardless of what cabin class you're in.

A photo vest loaded down with glass, bodies, and so on is a good option evidently, to make your carry on bag appear lighter, then pack it all back up once you're through security and in the terminal, or better in a lounge with less eyes on you!